A new class of nuclear magnetic resonance (NMR) experiments is applied to the characterization of structural and dynamic aspects of oligosaccharide-protein interactions that occur at cell surfaces. These interactions frequently mediate cell-cell contactsthat are important to host defense against invading organisms, to control of differentiation and activation of cells, and to recruitment of cells in events such as inflammatory response. Design of agents that can mimic or compete with natural participants in these interactions is important in combating disease. But,rational design of these reagents can only be undertaken with adequate molecular level descriptions of how key interactions occur. The long range goal of this project is providing this molecular level description. The specific approach is meant to provide a comparison of oligosaccharide structure and dynamics, in the whole range of environments over which the interactions occur; free in solution, bound to membrane, and bound to protein. NMR approaches that utilize orientational dependence as well as distance dependence of observables are uniquely suited to these investigations. Testing of this new methodology is a key component of the research. The primary systems selected for application and testing are C-type lectins and their carbohydrate ligands. These include the carbohydrate recognition domain of mannose binding protein, with its mannose or N-acetylglucosamine terminated ligands, and the carbohydrate recognition domains from a selectin, with its sialyl-Lewis" related ligands. Abnormal function of both systems relate to current health concerns.